Radio Frequency (RF) Power Amplifiers (PA) are widely used in a variety of RF based communication systems and applications such as mobile phones, cellular networks, and other electronic devices. RF power amplifiers are used in these devices to amplify RF signals in order to transmit the RF signals remotely. RF PAs are one of the most significant sources of power consumption in these communication systems, and their efficiency has a significant impact on the power supply in these communication systems. For example, mobile telephone makers make great efforts to increase the efficiency of the RF PA circuits, because the efficiency of the RF PA is one of the most critical factors determining the battery life of the mobile telephone and its talk time.
Several systems claim to reduce the power consumption of digital communication systems with high peak-to-average power ratio, such as OFDM (Orthogonal Frequency-Division Multiplexing), either by performing transforms in the digital domain to cancel the effect of the high peak-to-average ratio, or in the analog domain by changing the supply or bias of the power amplifier in order to adjust on the fly for the varying power ratio. The first type of systems are quite elegant in theory since they eliminate the effect of the high Peak-to-Average Power Ratio (PAPR) altogether, however even in the current very advanced semiconductor processes the amount of computation required to do so, and therefore the power consumption itself is quite substantial; which adversely affects the efficiency they set to improve in the first place.
The second type of systems recognize that the power amplifier has to operate linearly in order to transmit a signal with a low bit error rate, and therefore suitably change the supply or bias voltages of the amplifier in real time according to the data signal being transmitted. This type of systems may conserve power in principle by dynamically maintaining the minimum necessary supply levels on the power amplifier. However, in the prior art some part of the control circuits are also operating linearly and hence waste more power to respond fast enough. Changing the bias on the fly is also not practical, since linear circuits require time to adjust their linear operation for a changed bias condition; and inserting blank periods between transmitted symbols goes against the intrinsic advantages of orthogonal frequency type of communication systems.
To address these issues and to provide an RF power amplifier with an increased efficiency, an enhanced boosting solution for the supply of power amplifiers in high peak to average power ratio applications is required.
It is an object of the present invention to provide a system which is capable of boosting the supply of the power amplifier in high peak to average power ratio applications.
It is another object of the present invention to provide an RF power amplifier with an economic consumption of power.
Other objects and advantages of the invention will become apparent as the description proceeds.